Modular confined organic print head and system

ABSTRACT

Embodiments of the disclosed subject matter provide a vapor distribution manifold that ejects organic vapor laden gas into a chamber and withdraws chamber gas, where vapor ejected from the manifold is incident on, and condenses onto, a deposition surface within the chamber that moves relative to one or more print heads in a direction orthogonal to a platen normal and a linear extent of the manifold. The volumetric flow of gas withdrawn by the manifold from the chamber may be greater than the volumetric flow of gas injected into the chamber by the manifold. The net outflow of gas from the chamber through the manifold may prevent organic vapor from diffusing beyond the extent of the gap between the manifold and deposition surface. The manifold may be configured so that long axes of delivery and exhaust apertures are perpendicular to a print direction.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/225,040 filed Jan. 23, 2019, which claims priority to U.S. PatentApplication Ser. No. 62/633,797, filed Feb. 22, 2018, the entirecontents of each are incorporated herein by reference.

FIELD

The present invention relates to a confined organic printing (COP)system that can be added to a substrate processing chamber, and methodsof making organic light emitting diodes/devices (OLEDs) and otheroptoelectronic device using this chamber.

BACKGROUND

Opto-electronic devices that make use of organic materials are becomingincreasingly desirable for a number of reasons. Many of the materialsused to make such devices are relatively inexpensive, so organicopto-electronic devices have the potential for cost advantages overinorganic devices. In addition, the inherent properties of organicmaterials, such as their flexibility, may make them well suited forparticular applications such as fabrication on a flexible substrate.Examples of organic opto-electronic devices include organic lightemitting diodes/devices (OLEDs), organic phototransistors, organicphotovoltaic cells, and organic photodetectors. For OLEDs, the organicmaterials may have performance advantages over conventional materials.For example, the wavelength at which an organic emissive layer emitslight may generally be readily tuned with appropriate dopants.

OLEDs make use of thin organic films that emit light when voltage isapplied across the device. OLEDs are becoming an increasinglyinteresting technology for use in applications such as flat paneldisplays, illumination, and backlighting. Several OLED materials andconfigurations are described in U.S. Pat. Nos. 5,844,363, 6,303,238, and5,707,745, which are incorporated herein by reference in their entirety.

One application for phosphorescent emissive molecules is a full colordisplay. Industry standards for such a display call for pixels adaptedto emit particular colors, referred to as “saturated” colors. Inparticular, these standards call for saturated red, green, and bluepixels. Alternatively the OLED can be designed to emit white light. Inconventional liquid crystal displays emission from a white backlight isfiltered using absorption filters to produce red, green and blueemission. The same technique can also be used with OLEDs. The white OLEDcan be either a single EML device or a stack structure. Color may bemeasured using CIE coordinates, which are well known to the art.

As used herein, the term “organic” includes polymeric materials as wellas small molecule organic materials that may be used to fabricateorganic opto-electronic devices. “Small molecule” refers to any organicmaterial that is not a polymer, and “small molecules” may actually bequite large. Small molecules may include repeat units in somecircumstances. For example, using a long chain alkyl group as asubstituent does not remove a molecule from the “small molecule” class.Small molecules may also be incorporated into polymers, for example as apendent group on a polymer backbone or as a part of the backbone. Smallmolecules may also serve as the core moiety of a dendrimer, whichconsists of a series of chemical shells built on the core moiety. Thecore moiety of a dendrimer may be a fluorescent or phosphorescent smallmolecule emitter. A dendrimer may be a “small molecule,” and it isbelieved that all dendrimers currently used in the field of OLEDs aresmall molecules.

As used herein, “top” means furthest away from the substrate, while“bottom” means closest to the substrate. Where a first layer isdescribed as “disposed over” a second layer, the first layer is disposedfurther away from substrate. There may be other layers between the firstand second layer, unless it is specified that the first layer is “incontact with” the second layer. For example, a cathode may be describedas “disposed over” an anode, even though there are various organiclayers in between.

As used herein, “solution processible” means capable of being dissolved,dispersed, or transported in and/or deposited from a liquid medium,either in solution or suspension form.

A ligand may be referred to as “photoactive” when it is believed thatthe ligand directly contributes to the photoactive properties of anemissive material. A ligand may be referred to as “ancillary” when it isbelieved that the ligand does not contribute to the photoactiveproperties of an emissive material, although an ancillary ligand mayalter the properties of a photoactive ligand.

As used herein, and as would be generally understood by one skilled inthe art, a first “Highest Occupied Molecular Orbital” (HOMO) or “LowestUnoccupied Molecular Orbital” (LUMO) energy level is “greater than” or“higher than” a second HOMO or LUMO energy level if the first energylevel is closer to the vacuum energy level. Since ionization potentials(IP) are measured as a negative energy relative to a vacuum level, ahigher HOMO energy level corresponds to an IP having a smaller absolutevalue (an IP that is less negative). Similarly, a higher LUMO energylevel corresponds to an electron affinity (EA) having a smaller absolutevalue (an EA that is less negative). On a conventional energy leveldiagram, with the vacuum level at the top, the LUMO energy level of amaterial is higher than the HOMO energy level of the same material. A“higher” HOMO or LUMO energy level appears closer to the top of such adiagram than a “lower” HOMO or LUMO energy level.

As used herein, and as would be generally understood by one skilled inthe art, a first work function is “greater than” or “higher than” asecond work function if the first work function has a higher absolutevalue. Because work functions are generally measured as negative numbersrelative to vacuum level, this means that a “higher” work function ismore negative. On a conventional energy level diagram, with the vacuumlevel at the top, a “higher” work function is illustrated as furtheraway from the vacuum level in the downward direction. Thus, thedefinitions of HOMO and LUMO energy levels follow a different conventionthan work functions.

More details on OLEDs, and the definitions described above, can be foundin U.S. Pat. No. 7,279,704, which is incorporated herein by reference inits entirety.

SUMMARY

According to an embodiment, an organic light emitting diode/device(OLED) is also provided. The OLED can include an anode, a cathode, andan organic layer, disposed between the anode and the cathode. Accordingto an embodiment, the organic light emitting device is incorporated intoone or more device selected from a consumer product, an electroniccomponent module, and/or a lighting panel.

According to an embodiment, a system may include a vapor distributionmanifold that ejects organic vapor laden gas into a chamber andwithdraws chamber gas. The vapor ejected from the manifold may beincident on, and may condense onto, a deposition surface within thechamber that moves relative to one or more print heads in a directionorthogonal to a platen normal and a linear extent of the manifold. Thevolumetric flow of gas withdrawn by the manifold from the chamber may begreater than the volumetric flow of gas injected into the chamber by themanifold. The net outflow of gas from the chamber through the manifoldmay prevent organic vapor from diffusing beyond the extent of the gapbetween the manifold and deposition surface. The manifold may beconfigured so that long axes of delivery and exhaust apertures areperpendicular to a print direction.

The manifold may include one or more delivery apertures. The one or moredelivery apertures may be surrounded by exhaust apertures disposedbetween the delivery apertures and an edge of the manifold. The vapordistribution manifold may be formed from perforated sheets of metal. Thevapor distribution manifold may include one or more heated organic vaporsources. The vapor distribution manifold may be joined to a surroundingchamber wall via one or more connections, and wherein the connectionsare not heated. The vapor may be ejected to form a deposition on thedeposition surface has a flow where a Péclet number Pe <10 with respectto a binary diffusivity of a delivery gas and a confinement gas.

The system may have a process chamber that includes the vapordistribution manifold and an aperture assembly of the one or more printheads that both ejects organic vapor laden inert delivery gas into theprocess chamber and withdraws chamber gas. The vapor distributionmanifold may eject vapor that is incident on, and condenses onto, adeposition surface within the process chamber. The deposition surfacemay be configured to move relative to the print head in a directionorthogonal to the deposition surface normal and a linear extent of thevapor distribution manifold. A net outflow of gas from the processchamber through the vapor distribution manifold may prevent organicvapor from diffusing beyond a gap between the manifold and thedeposition surface. The aperture assembly may balance a deposition flowand an exhaust flow so that deposition material is confined to an areaunder the one or more print heads. The process chamber may becold-walled. The process chamber may include at least one of organicvapor jet printing (OVJP) equipment and metrology equipment. The processchamber may include at least one confined organic printer (COP) head andat least one organic vapor jet printing (OVJP) head. The process chambermay be operated at a pressure of between 50 and 300 Torr. The processchamber may be operated at a pressure of between 20 and 800 Torr. Theejected vapor may be incident on, and may condense onto, the depositionsurface within the process chamber without a shadow mask.

At least one of the one or more print heads of the system may depositdifferent organic species from the other print heads. At least one ofthe one or more print heads deposits the same organic species in thesame ratio or in different ratios than the other heads of the pluralityof COP heads. The one or more print heads may be adjacent to at leastone selected from the group consisting of: a common cold plate, and aconfinement gas distribution manifold. The deposition surface may be aplaten. The platen may be configured to hold a substrate. The platen maybe configured to be cooled by a cooling device. The deposition surfacemay be a portion of a roll of flexible material.

The system may include a deposition aperture to deposit gaseousprecursors or substances as deposition materials, and the depositionmaterials may be confined to a volume defined by the area under thedeposition apertures by a confining flow and localized exhaust. A shapeof the deposition aperture may have a first axis that is 10 timesgreater in length than a second axis. A shape of the deposition aperturemay be amorphous. A shape of the deposition aperture may match anunmasked area of a substrate on which the deposition materials aredeposited. The unmasked area may define an active device. The unmaskedarea may have been previously processed. A masked area may protect thesubstrate from the deposition materials. The masked area may be removedafter the deposition materials are deposited, where the removal of themasked area is by subsequent processing.

According to an embodiment, a method may include fabricating an organiclight emitting device (OLED). The method may include depositing a holetransport layer (HTL) with a selective area confined organic printer(COP) in a process chamber that includes an organic vapor jet printing(OVJP) print apparatus, and depositing at least one emissive layer withthe OVJP print apparatus when the deposition of the HTL is completed.

According to an embodiments, a method may include fabricating an organiclight emitting device (OLED). The method may include depositing a holetransport layer (HTL) with a selective area confined organic printer(COP) in a process chamber that includes an organic vapor jet printing(OVJP) print apparatus, and depositing the at least one emissive layerconcurrently with the HTL, but on top of the HTL layer, where the HTL isdeposited by COP and the EML is deposited by OVJP.

According to an embodiment, a method may include fabricating an organiclight emitting device (OLED) using one or more confined organic printer(COP) heads. The method may include depositing an organic thin filmlayer with graded doping in a plurality of passes by depositing materialof varying composition with each pass, where the composition of thematerial deposited by a single COP head of the one or more COP headsvaries with each pass.

According to an embodiment, a method may include fabricating an organiclight emitting device (OLED) using confined organic printer (COP) heads.The method may include depositing an organic thin film layer with gradeddoping in a plurality of passes by depositing material of varyingcomposition with each pass, where a plurality of the COP heads depositthe material of different composition on a substrate in series, whereinthe material composition deposited by each COP head is constant in time.The method may include depositing a plurality of organic layerscontaining different chemical species with the plurality of COP heads.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an organic light emitting device.

FIG. 2 shows an inverted organic light emitting device that does nothave a separate electron transport layer.

FIG. 3 shows an organic vapor jet printing (OVJP) process flow.

FIG. 4 shows a delivery-exhaust-confinement (DEC) type OVJP print head.

FIG. 5 shows a COP reactor of a COP system according to an embodiment ofthe disclosed subject matter.

FIG. 6 shows a deposition of an organic thin film on a substrate using aCOP head according to an embodiment of the disclosed subject matter.

FIG. 7 shows a substrate-facing tip of a COP head according to anembodiment of the disclosed subject matter.

FIG. 8 shows a simulated organic vapor concentration profile (left) andlines of gas flow (right) for the gap between a COP head and a substrateaccording to an embodiment of the disclosed subject matter.

FIGS. 9A-9B show average deposition thickness for a simulated COP headas a function of distance from the centerline along its width axis (top)and depth axis (bottom) according to an embodiment of the disclosedsubject matter.

FIG. 10 shows a material utilization efficiency of a simulated COP headas a function of multiple process variables according to an embodimentof the disclosed subject matter.

FIG. 11 shows a physical model of a COP head according to an embodimentof the disclosed subject matter.

FIG. 12 shows process flow diagram of a COP head according to anembodiment of the disclosed subject matter.

FIG. 13 shows a plot of helium fraction within a gap between a COP headand a substrate according to an embodiment of the disclosed subjectmatter.

FIG. 14 show a plot of and the value of organic diffusivity within thegap between a COP head and a substrate according to an embodiment of thedisclosed subject matter.

FIG. 15 shows a COP head with multiple sets of delivery and exhaustapertures arranged in a linear array according to an embodiment of thedisclosed subject matter.

DETAILED DESCRIPTION

Generally, an OLED comprises at least one organic layer disposed betweenand electrically connected to an anode and a cathode. When a current isapplied, the anode injects holes and the cathode injects electrons intothe organic layer(s). The injected holes and electrons each migratetoward the oppositely charged electrode. When an electron and holelocalize on the same molecule, an “exciton,” which is a localizedelectron-hole pair having an excited energy state, is formed. Light isemitted when the exciton relaxes via a photoemissive mechanism. In somecases, the exciton may be localized on an excimer or an exciplex.Non-radiative mechanisms, such as thermal relaxation, may also occur,but are generally considered undesirable.

The initial OLEDs used emissive molecules that emitted light from theirsinglet states (“fluorescence”) as disclosed, for example, in U.S. Pat.No. 4,769,292, which is incorporated by reference in its entirety.Fluorescent emission generally occurs in a time frame of less than 10nanoseconds.

More recently, OLEDs having emissive materials that emit light fromtriplet states (“phosphorescence”) have been demonstrated. Baldo et al.,“Highly Efficient Phosphorescent Emission from OrganicElectroluminescent Devices,” Nature, vol. 395, 151-154, 1998;(“Baldo-I”) and Baldo et al., “Very high-efficiency green organiclight-emitting devices based on electrophosphorescence,” Appl. Phys.Lett., vol. 75, No. 3, 4-6 (1999) (“Baldo-II”), are incorporated byreference in their entireties. Phosphorescence is described in moredetail in U.S. Pat. No. 7,279,704 at cols. 5-6, which are incorporatedby reference.

FIG. 1 shows an organic light emitting device 100. The figures are notnecessarily drawn to scale. Device 100 may include a substrate 110, ananode 115, a hole injection layer 120, a hole transport layer 125, anelectron blocking layer 130, an emissive layer 135, a hole blockinglayer 140, an electron transport layer 145, an electron injection layer150, a protective layer 155, a cathode 160, and a barrier layer 170.Cathode 160 is a compound cathode having a first conductive layer 162and a second conductive layer 164. Device 100 may be fabricated bydepositing the layers described, in order. The properties and functionsof these various layers, as well as example materials, are described inmore detail in U.S. Pat. No. 7,279,704 at cols. 6-10, which areincorporated by reference.

More examples for each of these layers are available. For example, aflexible and transparent substrate-anode combination is disclosed inU.S. Pat. No. 5,844,363, which is incorporated by reference in itsentirety. An example of a p-doped hole transport layer is m-MTDATA dopedwith F₄-TCNQ at a molar ratio of 50:1, as disclosed in U.S. PatentApplication Publication No. 2003/0230980, which is incorporated byreference in its entirety. Examples of emissive and host materials aredisclosed in U.S. Pat. No. 6,303,238 to Thompson et al., which isincorporated by reference in its entirety. An example of an n-dopedelectron transport layer is BPhen doped with Li at a molar ratio of 1:1,as disclosed in U.S. Patent Application Publication No. 2003/0230980,which is incorporated by reference in its entirety. U.S. Pat. Nos.5,703,436 and 5,707,745, which are incorporated by reference in theirentireties, disclose examples of cathodes including compound cathodeshaving a thin layer of metal such as Mg:Ag with an overlyingtransparent, electrically-conductive, sputter-deposited ITO layer. Thetheory and use of blocking layers is described in more detail in U.S.Pat. No. 6,097,147 and U.S. Patent Application Publication No.2003/0230980, which are incorporated by reference in their entireties.Examples of injection layers are provided in U.S. Patent ApplicationPublication No. 2004/0174116, which is incorporated by reference in itsentirety. A description of protective layers may be found in U.S. PatentApplication Publication No. 2004/0174116, which is incorporated byreference in its entirety.

FIG. 2 shows an inverted OLED 200. The device includes a substrate 210,a cathode 215, an emissive layer 220, a hole transport layer 225, and ananode 230. Device 200 may be fabricated by depositing the layersdescribed, in order. Because the most common OLED configuration has acathode disposed over the anode, and device 200 has cathode 215 disposedunder anode 230, device 200 may be referred to as an “inverted” OLED.Materials similar to those described with respect to device 100 may beused in the corresponding layers of device 200. FIG. 2 provides oneexample of how some layers may be omitted from the structure of device100.

The simple layered structure illustrated in FIGS. 1 and 2 is provided byway of non-limiting example, and it is understood that embodiments ofthe invention may be used in connection with a wide variety of otherstructures. The specific materials and structures described areexemplary in nature, and other materials and structures may be used.Functional OLEDs may be achieved by combining the various layersdescribed in different ways, or layers may be omitted entirely, based ondesign, performance, and cost factors. Other layers not specificallydescribed may also be included. Materials other than those specificallydescribed may be used. Although many of the examples provided hereindescribe various layers as comprising a single material, it isunderstood that combinations of materials, such as a mixture of host anddopant, or more generally a mixture, may be used. Also, the layers mayhave various sublayers. The names given to the various layers herein arenot intended to be strictly limiting. For example, in device 200, holetransport layer 225 transports holes and injects holes into emissivelayer 220, and may be described as a hole transport layer or a holeinjection layer. In one embodiment, an OLED may be described as havingan “organic layer” disposed between a cathode and an anode. This organiclayer may comprise a single layer, or may further comprise multiplelayers of different organic materials as described, for example, withrespect to FIGS. 1 and 2.

Structures and materials not specifically described may also be used,such as OLEDs comprised of polymeric materials (PLEDs) such as disclosedin U.S. Pat. No. 5,247,190 to Friend et al., which is incorporated byreference in its entirety. By way of further example, OLEDs having asingle organic layer may be used. OLEDs may be stacked, for example asdescribed in U.S. Pat. No. 5,707,745 to Forrest et al, which isincorporated by reference in its entirety. The OLED structure maydeviate from the simple layered structure illustrated in FIGS. 1 and 2.For example, the substrate may include an angled reflective surface toimprove out-coupling, such as a mesa structure as described in U.S. Pat.No. 6,091,195 to Forrest et al., and/or a pit structure as described inU.S. Pat. No. 5,834,893 to Bulovic et al., which are incorporated byreference in their entireties.

Unless otherwise specified, any of the layers of the various embodimentsmay be deposited by any suitable method. For the organic layers,preferred methods include thermal evaporation, ink-jet, such asdescribed in U.S. Pat. Nos. 6,013,982 and 6,087,196, which areincorporated by reference in their entireties, organic vapor phasedeposition (OVPD), such as described in U.S. Pat. No. 6,337,102 toForrest et al., which is incorporated by reference in its entirety, anddeposition by organic vapor jet printing (OVJP), such as described inU.S. Pat. No. 7,431,968, which is incorporated by reference in itsentirety. Other suitable deposition methods include spin coating andother solution based processes. Solution based processes are preferablycarried out in nitrogen or an inert atmosphere. For the other layers,preferred methods include thermal evaporation. Preferred patterningmethods include deposition through a mask, cold welding such asdescribed in U.S. Pat. Nos. 6,294,398 and 6,468,819, which areincorporated by reference in their entireties, and patterning associatedwith some of the deposition methods such as ink-jet and OVJD. Othermethods may also be used. The materials to be deposited may be modifiedto make them compatible with a particular deposition method. Forexample, substituents such as alkyl and aryl groups, branched orunbranched, and preferably containing at least 3 carbons, may be used insmall molecules to enhance their ability to undergo solution processing.Substituents having 20 carbons or more may be used, and 3-20 carbons isa preferred range. Materials with asymmetric structures may have bettersolution processibility than those having symmetric structures, becauseasymmetric materials may have a lower tendency to recrystallize.Dendrimer substituents may be used to enhance the ability of smallmolecules to undergo solution processing.

Devices fabricated in accordance with embodiments of the presentinvention may further optionally comprise a barrier layer. One purposeof the barrier layer is to protect the electrodes and organic layersfrom damaging exposure to harmful species in the environment includingmoisture, vapor and/or gases, etc. The barrier layer may be depositedover, under or next to a substrate, an electrode, or over any otherparts of a device including an edge. The barrier layer may comprise asingle layer, or multiple layers. The barrier layer may be formed byvarious known chemical vapor deposition techniques and may includecompositions having a single phase as well as compositions havingmultiple phases. Any suitable material or combination of materials maybe used for the barrier layer. The barrier layer may incorporate aninorganic or an organic compound or both. The preferred barrier layercomprises a mixture of a polymeric material and a non-polymeric materialas described in U.S. Pat. No. 7,968,146, PCT Pat. Application Nos.PCT/US2007/023098 and PCT/US2009/042829, which are herein incorporatedby reference in their entireties. To be considered a “mixture”, theaforesaid polymeric and non-polymeric materials comprising the barrierlayer should be deposited under the same reaction conditions and/or atthe same time. The weight ratio of polymeric to non-polymeric materialmay be in the range of 95:5 to 5:95. The polymeric material and thenon-polymeric material may be created from the same precursor material.In one example, the mixture of a polymeric material and a non-polymericmaterial consists essentially of polymeric silicon and inorganicsilicon.

Devices fabricated in accordance with embodiments of the invention canbe incorporated into a wide variety of electronic component modules (orunits) that can be incorporated into a variety of electronic products orintermediate components. Examples of such electronic products orintermediate components include display screens, lighting devices suchas discrete light source devices or lighting panels, etc. that can beutilized by the end-user product manufacturers. Such electroniccomponent modules can optionally include the driving electronics and/orpower source(s). Devices fabricated in accordance with embodiments ofthe invention can be incorporated into a wide variety of consumerproducts that have one or more of the electronic component modules (orunits) incorporated therein. A consumer product comprising an OLED thatincludes the compound of the present disclosure in the organic layer inthe OLED is disclosed. Such consumer products would include any kind ofproducts that include one or more light source(s) and/or one or more ofsome type of visual displays. Some examples of such consumer productsinclude flat panel displays, computer monitors, medical monitors,televisions, billboards, lights for interior or exterior illuminationand/or signaling, heads-up displays, fully or partially transparentdisplays, flexible displays, laser printers, telephones, mobile phones,tablets, phablets, personal digital assistants (PDAs), wearable devices,laptop computers, digital cameras, camcorders, viewfinders,micro-displays (displays that are less than 2 inches diagonal), 3-Ddisplays, virtual reality or augmented reality displays, vehicles, videowalls comprising multiple displays tiled together, theater or stadiumscreen, and a sign. Various control mechanisms may be used to controldevices fabricated in accordance with the present invention, includingpassive matrix and active matrix. Many of the devices are intended foruse in a temperature range comfortable to humans, such as 18 C to 30 C,and more preferably at room temperature (20-25 C), but could be usedoutside this temperature range, for example, from −40 C to 80 C.

The materials and structures described herein may have applications indevices other than OLEDs. For example, other optoelectronic devices suchas organic solar cells and organic photodetectors may employ thematerials and structures. More generally, organic devices, such asorganic transistors, may employ the materials and structures.

In some embodiments, the OLED has one or more characteristics selectedfrom the group consisting of being flexible, being rollable, beingfoldable, being stretchable, and being curved. In some embodiments, theOLED is transparent or semi-transparent. In some embodiments, the OLEDfurther comprises a layer comprising carbon nanotubes.

In some embodiments, the OLED further comprises a layer comprising adelayed fluorescent emitter. In some embodiments, the OLED comprises aRGB pixel arrangement or white plus color filter pixel arrangement. Insome embodiments, the OLED is a mobile device, a hand held device, or awearable device. In some embodiments, the OLED is a display panel havingless than 10 inch diagonal or 50 square inch area. In some embodiments,the OLED is a display panel having at least 10 inch diagonal or 50square inch area. In some embodiments, the OLED is a lighting panel.

In some embodiments of the emissive region, the emissive region furthercomprises a host.

In some embodiments, the compound can be an emissive dopant. In someembodiments, the compound can produce emissions via phosphorescence,fluorescence, thermally activated delayed fluorescence, i.e., TADF (alsoreferred to as E-type delayed fluorescence), triplet-tripletannihilation, or combinations of these processes.

The OLED disclosed herein can be incorporated into one or more of aconsumer product, an electronic component module, and a lighting panel.The organic layer can be an emissive layer and the compound can be anemissive dopant in some embodiments, while the compound can be anon-emissive dopant in other embodiments.

The organic layer can also include a host. In some embodiments, two ormore hosts are preferred. In some embodiments, the hosts used maybe a)bipolar, b) electron transporting, c) hole transporting or d) wide bandgap materials that play little role in charge transport. In someembodiments, the host can include a metal complex. The host can be aninorganic compound.

Combination with Other Materials

The materials described herein as useful for a particular layer in anorganic light emitting device may be used in combination with a widevariety of other materials present in the device. For example, emissivedopants disclosed herein may be used in conjunction with a wide varietyof hosts, transport layers, blocking layers, injection layers,electrodes and other layers that may be present. The materials describedor referred to below are non-limiting examples of materials that may beuseful in combination with the compounds disclosed herein, and one ofskill in the art can readily consult the literature to identify othermaterials that may be useful in combination.

Various materials may be used for the various emissive and non-emissivelayers and arrangements disclosed herein. Examples of suitable materialsare disclosed in U.S. Patent Application Publication No. 2017/0229663,which is incorporated by reference in its entirety.

Conductivity Dopants:

A charge transport layer can be doped with conductivity dopants tosubstantially alter its density of charge carriers, which will in turnalter its conductivity. The conductivity is increased by generatingcharge carriers in the matrix material, and depending on the type ofdopant, a change in the Fermi level of the semiconductor may also beachieved. Hole-transporting layer can be doped by p-type conductivitydopants and n-type conductivity dopants are used in theelectron-transporting layer.

HIL/HTL:

A hole injecting/transporting material to be used in the presentinvention is not particularly limited, and any compound may be used aslong as the compound is typically used as a hole injecting/transportingmaterial.

EBL:

An electron blocking layer (EBL) may be used to reduce the number ofelectrons and/or excitons that leave the emissive layer. The presence ofsuch a blocking layer in a device may result in substantially higherefficiencies, and or longer lifetime, as compared to a similar devicelacking a blocking layer. Also, a blocking layer may be used to confineemission to a desired region of an OLED. In some embodiments, the EBLmaterial has a higher LUMO (closer to the vacuum level) and/or highertriplet energy than the emitter closest to the EBL interface. In someembodiments, the EBL material has a higher LUMO (closer to the vacuumlevel) and or higher triplet energy than one or more of the hostsclosest to the EBL interface. In one aspect, the compound used in EBLcontains the same molecule or the same functional groups used as one ofthe hosts described below.

Host:

The light emitting layer of the organic EL device of the presentinvention preferably contains at least a metal complex as light emittingmaterial, and may contain a host material using the metal complex as adopant material. Examples of the host material are not particularlylimited, and any metal complexes or organic compounds may be used aslong as the triplet energy of the host is larger than that of thedopant. Any host material may be used with any dopant so long as thetriplet criteria is satisfied.

HBL:

A hole blocking layer (HBL) may be used to reduce the number of holesand/or excitons that leave the emissive layer. The presence of such ablocking layer in a device may result in substantially higherefficiencies and/or longer lifetime as compared to a similar devicelacking a blocking layer. Also, a blocking layer may be used to confineemission to a desired region of an OLED. In some embodiments, the HBLmaterial has a lower HOMO (further from the vacuum level) and or highertriplet energy than the emitter closest to the HBL interface. In someembodiments, the HBL material has a lower HOMO (further from the vacuumlevel) and or higher triplet energy than one or more of the hostsclosest to the HBL interface.

ETL:

An electron transport layer (ETL) may include a material capable oftransporting electrons. The electron transport layer may be intrinsic(undoped), or doped. Doping may be used to enhance conductivity.Examples of the ETL material are not particularly limited, and any metalcomplexes or organic compounds may be used as long as they are typicallyused to transport electrons.

Charge Generation Layer (CGL)

In tandem or stacked OLEDs, the CGL plays an essential role in theperformance, which is composed of an n-doped layer and a p-doped layerfor injection of electrons and holes, respectively. Electrons and holesare supplied from the CGL and electrodes. The consumed electrons andholes in the CGL are refilled by the electrons and holes injected fromthe cathode and anode, respectively; then, the bipolar currents reach asteady state gradually. Typical CGL materials include n and pconductivity dopants used in the transport layers.

Organic vapor jet printing (OVJP) is a technique for producing preciselypatterned organic thin films on a substrate without the use of solventsor shadow masks, and FIG. 3 shows an OVJP process flow. Organicmaterials may be evaporated in heated furnaces 301 and entrained instreams of inert carrier gas 302 henceforth referred to as delivery gas.Delivery gas steams may combine in a mixing zone 303 to enableco-deposition of host and dopant materials from different source ovens.The mixed gas and vapor stream may be collimated by an array of one ormore nozzles 304 into jets 305 that carry the vapor to the substrate306. The organic vapors may condense into well-defined spots of thinfilm on the regions of the substrate where the jets impinge. Patterns oforganic thin film may be drawn by moving the substrate relative to thenozzle assembly. This technique is disclosed in U.S. Pat. No. 7,431,962.It is typically used for drawing arrays of disconnected features, ratherthan broad area patterning.

Early implementations of the OVJP process had overspray of organicmaterial that failed to deposit in the intended printing zone. This maybe remedied using DEC (delivery-exhaust-confinement) depositors that usea confinement flow to block the spread of surplus organic vaporunderneath the nozzle array and sweep it into exhaust channels forremoval, as described in U.S. Patent Publn. No. 2015/0376787.

FIG. 4 shows a delivery-exhaust-confinement (DEC) type OVJP print head.Each depositor may include one or more delivery apertures 401 thatinject organic laden delivery gas onto a deposition zone. The aperturesmay be surrounded by associated exhaust apertures 402 that withdraw thedelivery and confinement flows, along with excess organic vapor, fromthe deposition zone. A portion of the organic material 403 ejected bythe delivery aperture may condense on the substrate within the desiredprinting zone 404. Molecules of organic vapor 405 that fail to adhere tothe substrate may be flushed away from the substrate through the exhaustaperture. Confinement gas may enter from the edges of the depositor 406to push surplus organic vapor into the exhaust channels. No substantialexchange of organic vapor may take place between each depositor and thevolume of gas surrounding it. These isolated depositors 407 may betypically arranged in a linear array 408 coplanar with a substrate thatis perpendicular to the direction of motion during printing. Thisresults in an array of printed stripes 409 which may have no significantdeposition of organic material in the regions between stripes 410.Confinement and exhaust flows may act to isolate regions of intendeddeposition both from each other and from their surrounding environment.Depositors may perform similarly regardless of whether they are situatednear the ends or the midline of the array.

Because each depositor may be isolated from its surroundings, the DECsystem may prevent the chamber from becoming contaminated by excessorganic material from the printing process. While this generally may notbe a concern when printing small features, it may potentially be animportant for a tool for printing larger features. A deposition tool forprinting wide stripes of uniformly thick thin film with well-definededges may be used to deposit continuous films such as the transportlayers of an OLED array. OVJP systems that deposit large (>1 mm)features exist (Arnold et al. 2008) (Biswas et al. 2012), howeveroverspray control may be generally poor. Furthermore, the thicknessprofiles of printed features may tend to be Gaussian as opposed to themesa shaped profiles desired for organic optoelectronic devices, whichare more uniform across the deposition zone.

Large area organic thin films may be generally deposited from the vaporphase by either VTE (vacuum thermal evaporation) or OVPD (organic vaporphase deposition). Both techniques may use shadow masks to preventorganic material from being deposited in regions of a substrate where itwould be detrimental, such as encapsulation regions or busline contacts.Both techniques may contaminate their deposition chambers. Organicmaterial in VTE may spread by line of sight from the heated source, andOVPD reactors may be permeated with organic vapor entrained in hotcarrier gas. This may usually preclude using a single OVPD or VTEchamber to deposit multiple materials in a production setting. The wallsof an OVPD reactor may be typically heated to prevent the condensationof organic material onto the chamber walls. Both OVPD and VTE may havedifficulty achieving uniform deposition over a large substrate.

The embodiments of the disclosed subject matter address problems ofmasking, uniformity, and chamber contamination may exist for large-areaorganic thin film deposition techniques. Confined organic printing (COP)may be an adaption of DEC OVJP for printing intermediate to large sizefeatures (0.001-1 m). Instead of using the micro-environments created byconfinement flow to isolate multiple depositors and preventcross-contamination between printed features, COP may use confinementflow to isolate a single deposition zone from the surrounding chamber.This may be achieved by changing the orientation of the delivery andexhaust apertures so that they are perpendicular to the direction ofprinting, rather than parallel as they are in DEC OVJP.

This change of depositor orientation may replace the narrow nozzle ofmost OVJP implementations with a broad deposition aperture thatdistributes delivery flow evenly across the width of the depositionzone. It may be analogous to a slot die coater used in solvent basedprocessing. This configuration may allow wide features to be printed ina single pass with excellent film thickness uniformity. COP may provideimproved scaling over competing technologies, since larger substratesmay be coated by simply stitching together larger raster patternswithout increasing the area of the depositor. COP may deposit organicthin films with well-defined edges. This may eliminate the need forusing shadow masks, as well as their associated hardware and processsteps, in low-resolution patterning applications.

Embodiments of the disclosed subject matter may make it possible toperform multiple processing steps within the same chamber. COP may beintegrated into the same chamber as both OVJP and metrology processes.The disclosed embodiments providing multiple process steps within thesame chamber may provide many economic and technical advantages.Firstly, the embodiments of the disclosed subject matter may lowercapital costs by using fewer process vessels, and correspondingly fewerloadlocks, valves, substrate handling robots, and the like. Secondly,substrates may be moved between process steps more rapidly if complextransfers are not needed, thereby reducing TAKT time. Finally, beingable to rapidly transition between process steps may reduce thepotential for sensitive heterojunctions to become contaminated duringthe lag time between the applications of each layer. Contamination ofthe hole transport layer to emissive layer interface, for example, maysignificantly reduce the lifetime of OLEDs (Yamamoto et al. 2012).Multiple COP heads may be used to deposit a multilayer organic thin filmin a single chamber. Since a relatively small area of substrate isprinted at a time, the heads may be deployed to minimize the timeinterval between the deposition of the first and last organic film layerat each region of the substrate. Harmful exposure to the chamber ambientmay be minimized.

COP may advantageously sequester captured material in one place forreprocessing, providing economic and environmental advantages.

A confined organic printer (COP) may be configured to work in amulti-process chamber without contaminating the chamber or surroundingprocess equipment with organic material. To eliminate chambercontamination, the COP head may contain delivery gas distribution,evacuate the delivery gas and any non-condensed organic material, andprevent delivery gas and organic material from escaping the COPdeposition zone. This may be achieved by using three separate gas flows.The first gas flow may be a delivery gas saturated with organic vaporwhich flows through a centrally located aperture in a direction normalto the substrate surface. The second gas flow may be an evacuation flow(vacuum) surrounding the carrier gas aperture. The third gas flow may bea confinement flow, drawn inward along the substrate surface from thegas ambient surrounding the deposition zone towards the exhaustaperture. The confinement flow may prevent contamination of the processchamber by sweeping delivery gas and any organic material that has notcondensed on the substrate surface outward through the exhaust aperture.

The operation of the COP head may be similar to the OVJP processdescribed in U.S. Patent Publn. No. 2015/0376797. A distinction betweenthe two techniques is the COP print head of the embodiments of thedisclosed subject matter may deposit over a larger area than OVJP. Inthe case of OVJP, the primary function of confinement flow may be toisolate adjacent zones of the substrate surface from each other in orderto eliminate the overspray of organic vapor onto regions of substratewhere deposition is not desired. In the case of COP, however, theconfinement flow may act to isolate the surrounding chamber from thedeposition zone on the substrate, rather than enable printing of finefeatures on the substrate. The COP head may deposit contiguous zone onthe substrate defined by the delivery and exhaust aperture lengths. Theedges of the features printed by COP may not be as sharp as thoseprinted by OVJP. However, the resolution that may be achieved by COP issuch that it generally does not use shadow masks to confine the area ofdeposition.

The velocity of the organic vapor may be high in the case of OVJP, whenforming a jet. The velocity in organic vapor may be low in the case ofCOP, when no jet is formed. Convective transport may not dominate overbinary gas diffusivity between delivery and confinement flows. Inembodiments of the disclosed subject matter, the system may beconfigured such that Pe<1, where Pe is the Péclet number of the system.The Péclet number indicates the ratio of convective to diffusive masstransport in a flowing mixture. It is defined in this case as Pe=lu/Dwhere l is the characteristic length, u is the characteristic velocityof the delivery gas, and D is the binary diffusivity of helium deliverygas in argon confinement gas. In an example embodiment, l=1 mm, u=0.025to 0.25 m/s, and D=1×10⁻⁴ m²/s, as may be typical for a COP headoperating with He delivery and Ar confinement gas. Pe may be between0.25 and 0.025 in this case. So long as Pe is of order unity or less,convective transport may not dominate diffusive transport of deliveryand confinement gas.

Embodiments of the disclosed subject matter shown in FIGS. 5-15 mayprovide a system may include a vapor distribution manifold that ejectsorganic vapor laden gas into a chamber and withdraws chamber gas. Thevapor ejected from the manifold may be incident on, and may condenseonto, a deposition surface within the chamber that moves relative to oneor more print heads in a direction orthogonal to a platen normal and alinear extent of the manifold. The volumetric flow of gas withdrawn bythe manifold from the chamber may be greater than the volumetric flow ofgas injected into the chamber by the manifold. The net outflow of gasfrom the chamber through the manifold may prevent organic vapor fromdiffusing beyond the extent of the gap between the manifold anddeposition surface. The manifold may be configured so that long axes ofdelivery and exhaust apertures are perpendicular to a print direction.

The manifold may include one or more delivery apertures. The one or moredelivery apertures may be surrounded by exhaust apertures disposedbetween the delivery apertures and an edge of the manifold. The vapordistribution manifold may be formed from perforated sheets of metal andmay include one or more heated organic vapor sources. The vapordistribution manifold may be joined to a surrounding chamber wall viaone or more connections which may not be heated. The vapor may beejected to form a deposition on the deposition surface has a flow wherea Péclet number Pe<10 with respect to a binary diffusivity of a deliverygas and a confinement gas.

Embodiments of the disclosed subject matter may include a system havinga process chamber that includes the vapor distribution manifold and anaperture assembly of the one or more print heads that both ejectsorganic vapor laden inert delivery gas into the process chamber andwithdraws chamber gas. The vapor distribution manifold may eject vaporthat is incident on, and condenses onto, a deposition surface within theprocess chamber. The deposition surface may be configured to moverelative to the print head in a direction orthogonal to the depositionsurface normal and a linear extent of the vapor distribution manifold. Anet outflow of gas from the process chamber through the vapordistribution manifold may prevent organic vapor from diffusing beyond agap between the manifold and the deposition surface. The apertureassembly may balance a deposition flow and an exhaust flow so thatdeposition material is confined to an area under the one or more printheads.

The process chamber of the system may be cold-walled. The processchamber may include at least one of organic vapor jet printing (OVJP)equipment and metrology equipment. The process chamber may include atleast one confined organic printer (COP) head and at least one organicvapor jet printing (OVJP) head. The process chamber may be operated at apressure of between 50 and 300 Torr, or may be operated at a pressure ofbetween 20 and 800 Torr. The ejected vapor may be incident on, and maycondense onto, the deposition surface within the process chamber withouta shadow mask.

At least one of the one or more print heads of the system may depositdifferent organic species from the other print heads. At least one ofthe one or more print heads deposits the same organic species in thesame ratio or in different ratios than the other heads of the pluralityof COP heads. The one or more print heads may be adjacent to at leastone selected from the group consisting of: a common cold plate, and aconfinement gas distribution manifold. The deposition surface may be aplaten. The platen may be configured to hold a substrate. The platen maybe configured to be cooled by a cooling device. The deposition surfaceis a portion of a roll of flexible material.

The system may include a deposition aperture to deposit gaseousprecursors or substances as deposition materials, and the depositionmaterials may be confined to a volume defined by the area under thedeposition apertures by a confining flow and localized exhaust. A shapeof the deposition aperture may have a first axis that is 10 timesgreater in length than a second axis. A shape of the deposition aperturemay be amorphous. A shape of the deposition aperture may match anunmasked area of a substrate on which the deposition materials aredeposited. The unmasked area may define an active device. The unmaskedarea may have been previously processed. A masked area may protect thesubstrate from the deposition materials. The masked area may be removedafter the deposition material are deposited, where the removal of themasked area is by subsequent processing.

Embodiments of the disclosed subject matter may include a method offabricating an organic light emitting device (OLED). The method mayinclude depositing a hole transport layer (HTL) with a selective areaconfined organic printer (COP) in a process chamber that includes anorganic vapor jet printing (OVJP) print apparatus and depositing atleast one emissive layer with the OVJP print apparatus when thedeposition of the HTL is completed.

Embodiments of the disclosed subject matter may include a method offabricating an organic light emitting device (OLED). The method mayinclude depositing a hole transport layer (HTL) with a selective areaconfined organic printer (COP) in a process chamber that includes anorganic vapor jet printing (OVJP) print apparatus, and depositing the atleast one emissive layer concurrently with the HTL, but on top of theHTL layer, where the HTL is deposited by COP and the EML is deposited byOVJP.

A method may include fabricating an organic light emitting device (OLED)using one or more confined organic printer (COP) heads. The method mayinclude depositing an organic thin film layer with graded doping in aplurality of passes by depositing material of varying composition witheach pass, where the composition of the material deposited by a singleCOP head of the one or more COP heads varies with each pass.

In embodiments of the disclosed subject matter, a method may includefabricating an organic light emitting device (OLED) using confinedorganic printer (COP) heads. The method may include depositing anorganic thin film layer with graded doping in a plurality of passes bydepositing material of varying composition with each pass, where aplurality of the COP heads deposit the material of different compositionon a substrate in series, wherein the material composition deposited byeach COP head is constant in time. The method may include depositing aplurality of organic layers containing different chemical species withthe plurality of COP heads.

FIG. 5 shows a COP reactor of a COP system according to an embodiment ofthe disclosed subject matter. The COP system may include a gasdistribution manifold 501 (henceforth referred to as the COP head)disposed over a deposition substrate 502 in a cold-walled processchamber 503 that is sealed to permit operation at sub-atmosphericpressure and eliminate outside contamination. The COP head 501 shown inFIG. 5 may deposit material over an area that is much wider than it isdeep, and may use its translational motion relative to the substrate toachieve coverage over a large surface area. Configurations other thanlinear, such as square, round or an arbitrary shape are possible. Thearrangement shown in FIG. 5 may be a cross section normal to the longaxis of the COP head 501. The substrate 502 may typically be glass,although metal, ceramic, polymer, or semiconductor substrates may beused instead. The substrate 502 may be a flat plate, as shown in FIG. 5,or it may be a section of web in a roll-to-roll process. The chamber 503may include a device to move the substrate 502 relative to the printhead a direction orthogonal to both the long axis of the COP head 501and the substrate normal. The device may be a robotic substrate stage504 or may be moving rollers in a roll-to-roll process. Alternately, theCOP head 501 can be moved while the substrate 502 remains stationary.The chamber 503 may have additional equipment 505 unrelated to theaforementioned COP deposition process, including but not limited to, COPheads 501 depositing dissimilar materials, OVJP print heads, or thinfilm characterization equipment that acts on the same substrate 502.

The chamber 503 may be filled with inert gas, which may be argon, at apressure of between 50 and 760 Torr. The region around the COP head 501may be surrounded with nozzles 506 that may flood the deposition regionwith ultra-pure confinement gas, which may be argon. COP may depositmany of the same materials as vacuum thermal evaporation (VTE) withoutusing an ultrahigh vacuum to maintain process cleanliness. Embodimentsof the disclosed subject matter may have a substantially lower cost ofownership than existing organic thin film growth tools of comparablecapability, since ultrahigh vacuum equipment may be expensive to build,operate, and maintain. Operating in a non-high vacuum environment, suchas in the embodiments of the disclosed subject matter, may have otheradvantages, since technologies reliant on the presence of a gaseousmedium, such as convective cooling, ultrasonic sensing, and vacuumfixturing may be used. Solvent based deposition processes such as slotdie coating or inkjet printing may be potentially be integrated into thesame chamber as the COP head 501.

Chamber gasses may transport heat away from the heated portions of theCOP head 501, and may potentially create hot spots on the substrate 502or chamber 503. This may be mitigated through the use of a chiller plate507 between the COP head and the substrate. The chiller plate 507,disclosed in U.S. Patent Publn. No. 2012/097495, may place an activelycooled metal plate between the upper portions of the COP head 501 andthe substrate 502. The chiller plate 507 may include a cutout throughwhich the tip of the COP head 501 protrudes. The gap 508 between the COPhead 501 and the substrate 502, henceforth referred to as the flyheight, may be a well-controlled value of approximately 1 mm.

The COP head 501 may operate differently from large area depositionprocesses such as VTE by depositing organic material on relatively smallareas of a substrate at a time. FIG. 6 shows a deposition of an organicthin film on a substrate using a COP head according to an embodiment ofthe disclosed subject matter. In FIG. 6, the printing process may be onthe substrate in a face-up orientation. The substrate may move relativeto the COP head, so the region of substrate under the COP head moves aswell. The COP print head may generate a wide, thin region of organicvapor deposition 601 underneath it, and may be trailed by a continuousfilm 602. The motion of the deposition region in a direction mutuallyorthogonal to the substrate normal and long axis of the depositionregion, referred to as they axis, may form a wide (>1 cm) stripe oforganic thin film on the substrate. If additional stripes 603 aredesired, the substrate may be moved parallel to the long axis of thedeposition region, referred to as the x axis, between y axis passes.Similarly, wider stripes may be formed by drawing a raster pattern, withmultiple y axis passes offset along the x axis.

FIG. 7 shows a substrate-facing tip of a COP head according to anembodiment of the disclosed subject matter. That is, FIG. 7 shows theCOP head 501 as viewed from the perspective of the substrate normal. Along narrow delivery aperture 701 may eject organic vapor entrainedwithin an inert carrier gas, henceforth referred to as delivery gas,onto the substrate. The mixture of delivery gas and organic vapor mayimpinge on the substrate and the organic vapor condenses on thesubstrate. Delivery gas and uncondensed organic vapor may be removed orsucked out of the deposition zone, along with a portion of the gasambient surrounding COP head through exhaust apertures 702. The gasambient may be referred to confinement gas and may act to protect thechamber environment from the COP head 501 by establishing a netconvective current towards the print head that prevents organic materialfrom diffusing away from the COP head and throughout the chamber. Theconfinement gas in the embodiments of the disclosed subject matter maybe similar to the confinement gas disclosed in U.S. Patent Publn. No.2015/0376797. The delivery aperture 701 and exhaust aperture 702 may besurrounded by a spacer 703. As in FIG. 4, the COP head 501 may besurrounded by a chiller plate 507 that may contain distribution nozzles506 for the confinement gas. By distributing the confinement gasproximally to the COP head 501, it may be possible to isolate the COPhead 501 from the surrounding chamber ambient so that all streamlines offlow terminating at the COP head 501 originate in the confinement gasdistribution nozzles 506. This dedicated confinement gas flow may bedrawn from an ultrapure source to minimize substrate exposure toresidual gases such as O₂ and H₂O or remnants of a different depositionthat may be present in other regions of the chamber. The confinement gasmay be supplied by the chamber ambient and may flow between the coldplate and substrate towards the print head.

Simulation of this process using COMSOL Multiphysics CFD softwarepredicts the interaction of the delivery and confinement gas streams andthe anticipated deposition rates throughout the chamber. FIG. 8 shows asimulated organic vapor concentration profile (left) and lines of gasflow (right) for the gap between a COP head and a substrate according toan embodiment of the disclosed subject matter. That is, FIG. 8 shows thesimulated results for a cross section normal to the linear (x) axis ofthe COP head. The grayscale plot on the left hand side may show theconcentration of organic vapor within the deposition zone. Light regionsmay indicate regions of high organic vapor saturation C/C*, where C isthe concentration of organic vapor and C* is the concentration, presumedto be the saturation concentration, at the upstream portion of thedelivery channel 801. The delivery channel may terminate in a deliveryaperture 701 at its downstream lower portion. A large gradient in theconcentration field 802 may be present beneath the delivery aperture 701due to the condensation of organic vapor on the substrate. Organic vaporthat spreads laterally beyond the spacer 703 may be captured by theexhaust aperture 702 and removed from the deposition zone through anexhaust channel 803. The concentration of organic vapor in the exhaustchannel 803 may be low, due to both the adsorption of organic vapor tothe substrate and the dilution of the delivery flow by confinement gas.Confinement gas may flow from the outside edge of the gap between theCOP head 501 and substrate 804. The confinement gas may carry no organicvapor.

The flow streamlines of delivery gas 805 and confinement gas 806 may bedepicted on the right hand side of FIG. 8. The two flows 805, 806 maymove antiparallel to each other in the deposition region. The flows maymeet along a virtual boundary called the stagnation plane 807 where thehorizontal (y) axis velocity of each flow may be 0. The inward movementof the confinement gas 806 may prevent organic vapor from diffusingsubstantially beyond the stagnation plane. The delivery and confinementflows 805 and 806 along the stagnation plane may both acceleratevertically towards the exhaust aperture as they approach the stagnationplane 807.

FIGS. 9A-9B show average deposition thickness for a simulated COP headas a function of distance from the centerline along its width axis (top)and depth axis (bottom) according to an embodiment of the disclosedsubject matter. The deposition profiles may be predicted along a line ofsubstrate for a COP print head with a 20 mm long by 0.5 mm wide deliveryaperture, where helium delivery gas and confinement gas is assumed. Thedelivery gas flow rate may be 100 sccm and the exhaust flow rate may be200 sccm (standard cubic centimeters per minute). The chamber ambientmay be 200 Torr and 20° C., while the COP head may be heated to 300° C.The delivery aperture may be 0.5 mm wide, the exhaust apertures may be 1mm wide. The distance between the delivery aperture and exhaust aperturemay be 0.5 mm.

The deposition thickness along the width of the COP head may be plottedalong the x axis as a function of distance from the centerline as shownin FIG. 9A. There may be little deposition in regions not covered by thedelivery aperture 901, however deposition thickness may rise sharply 902for regions under the depositor. The center of the profile may be abroad mesa 903 over which thickness uniformity of better than ±3% can beexpected for the deposited stripe of organic material over the 20 mmwidth of the COP head delivery aperture.

In embodiments of the disclosed subject matter, multiple stripes may bestitched together by offsetting multiple passes along the x axis forwider films.

FIG. 9B shows the distribution of deposition thickness on the substrateas a function of y axis position centered along the delivery aperture.The deposition peaks 904 may be directly underneath the deliveryaperture. The profile may be roughly Gaussian with a 6σ width 905 ofabout 5 mm, corresponding to slightly more than the width of thedeposition aperture, spacers and exhaust apertures. There may bevirtually no organic material deposited beyond the exhaust apertures906, implying that no organic material is available for depositionoutside of the region bordered by the exhaust apertures. The rest of thechamber may be effectively isolated from the organic vapor used in theCOP process.

FIG. 10 shows a material utilization efficiency of a simulated COP headas a function of multiple process variables according to an embodimentof the disclosed subject matter. In particular, FIG. 10 shows theexpected deposition efficiency, meaning the fraction of organic materialthat may be ejected from the delivery aperture that may adsorbs on thesubstrate, as a function of the rate of delivery gas flow QD, fly heightbetween the COP head and substrate g, and exhaust spacer width DE. Flowthrough the exhaust channel may be assumed to be 2×QD in all cases.Deposition efficiency may be between 50 and 90% in most cases. Ingeneral, deposition efficiency may increase for reduced delivery flowrates, since organic vapor has more time to diffuse onto the substratein a slower gas flow. This may be at the expense of overall depositionrate, which may scale with delivery flow rate. Deposition efficiency mayincrease with decreased fly height, since the gap that organic vaporcrosses to reach the substrate may become smaller. While very efficientoperation may be achieved by bringing the COP head into close proximitywith the substrate, the minimum fly height may depend on factors likethe thermal load that may be handled by the substrate or the mechanicaltolerances of process tool. Deposition efficiency may be dependent onthe width of the DE spacer. Wider spacers may permit more efficientdeposition by increasing the path length of the delivery flow andtherefore the amount of time for organic vapor molecules to adsorb ontothe substrate. The maximum width of the DE spacer may be determined bythermal and mechanical considerations as well.

FIG. 11 shows a physical model of a COP head according to an embodimentof the disclosed subject matter. The head may include a clamp having astack of metal foil plates 1101 that may combine to form a gasdistribution manifold. The plates may include cutouts so that the gapsbetween layers of the stack form the delivery and exhaust aperturesshown in FIG. 6 at the lower tip of the stack 1102 facing the substrate.This design may be analogous to the plate stacking for construction ofOVJP print heads disclosed in U.S. Pat. No. 9,583,707 by UniversalDisplay Corp. The major side of the clamp 1103 may include channels todistribute delivery gas and remove exhaust from the stacked sheetmanifold. The delivery gas path may include an internal cavitycontaining a crucible of condensed organic material that may act as asublimation oven and may provide a source of organic material. Thecrucible may be accessed through a port 1104 on the side of the head.Placing the organic vapor source within the COP head may minimize theheated path length of organic material, simplifying thermal managementof the system and making it more self-contained. The major side of theclamp may be ported with vias 1105 connecting the COP head to processgas streams to provide regulated delivery and dilution flows, as well asa negative pressure exhaust stream. The metal plates 1101 may be held tothe major side of the clamp by pressure from the minor side of the clamp1106.

FIG. 12 shows process flow diagram of a COP head according to anembodiment of the disclosed subject matter. The delivery flow stream1201 may be metered by a mass flow controller (MFC) 1202. The deliveryflow may enter the organic source oven within the COP head, where it maypick up organic vapor from evaporable material inside of a crucible1203. The delivery flow may join up with the dilution flow 1204 at a tee1205 within the COP head downstream of the source oven. Dilution gasflow may be regulated by an MFC 1206. The delivery and/or dilution flowmay pass through the delivery aperture of the COP head 701. Exhaust flow1207 may enter the COP head and pass through a regulator 1208, either amass flow controller or upstream pressure controller, before being drawninto a vacuum reservoir 1211.

The dilution flow line may act as a bypass, shorting the organic vaporsource to the vacuum reservoir, skipping the delivery and exhaustapertures. When it is operated in this mode, the MFCs regulating inflow1202, 1206 may be closed and flow through the portions of the dilutionline within the COP head reverses. Flow from the dilution line maytravel down a bypass line 1209 to an open MFC 1210 connected with avacuum reservoir. When the COP head is in bypass mode, the downstreamMFC may generally have a higher setpoint than the MFC regulatingdelivery flow. This may create a reverse flow through the deliverychannel that prevents leakage of organic vapor onto the substrate. Thebypass may be used to turn off organic deposition while keeping theorganic source in a hot, vapor-producing state. Because source operationis dependent on absolute pressure, while flows are governed by smallerchanges in relative pressure, the bypass function may be used to rapidlymodulate deposition on and off while minimizing the transientdisturbances experienced by the organic vapor source. As an alternativeto regulating the flow through the bypass circuit, the pressurecontrollers may be used rather than mass flow controllers. In this case,the pressure set point of the bypass pressure controller may be set to avalue lower than the chamber pressure to establish flow from the chamberthrough the deposition aperture to the vacuum reservoir. The use of abypass may prevent contamination of the chamber when the COP head is notin use and any unused material may be collected and recycled.

FIG. 13 shows a plot of helium fraction within a gap between a COP headand a substrate according to an embodiment of the disclosed subjectmatter. Light delivery gas, such as helium, and a heavy confinement gas,such as argon may be used. The mole fraction of helium within thedeposition region is shown in FIG. 13. Gas at the upstream portion ofthe delivery channel may have a helium mole fraction X1=1 1301. The gasat the outer periphery of the COP head may be argon, so X1=0 at theoutside boundary 1302 where the confinement gas may be sourced. Thedistribution of helium is shown on the left-hand side of FIG. 13, with agray scale 1303 indicating mole fraction of helium. Gas flows may berelatively slow compared to the rate of diffusion of helium in argon, sogas transport may be dominated by diffusion. The mole fraction of heliummay follow a smooth gradient along the delivery gas flow path 1304, fromthe top of the delivery channel through the delivery aperture 701, underthe delivery-exhaust spacer 703, and out through the exhaust aperture702. Despite the addition of argon, the Péclet number may be stillrelatively low, such that Pe=0.1-1. There may be a substantial diffusivemixing between the delivery and confinement gas streams. Gas within theexhaust channel 1305 may be well mixed and may have a mole fraction ofX1=0.5, reflecting the 1:1 ratio of delivery and confinement flows. Themole fraction of helium along the confinement gas flow path 1306 mayvary from X1=0 at the confinement gas source to X1=0.5 in the exhaustchannel.

FIG. 14 show a plot of and the value of organic diffusivity within thegap between a COP head and a substrate according to an embodiment of thedisclosed subject matter. The diffusivity of organic vapor in the gasmixture shown in FIG. 14 may be determined by kinetic theory (Deen 1998)and may be dependent on the mole fraction of helium (Fairbanks andWilke, 1950). The gas diffusivity may be expressed by a grayscale 1401with units of 10⁻⁵ m²/s. The diffusion of organic vapor inside thedelivery channel 1402 may be very rapid, however convective transportmay dominate in this region. The elevated concentration of helium underthe delivery aperture 1403 may increase the rate at which organic vapordiffuses to the substrate. While diffusivity scales primarily withhelium mole fraction, it may become slower closer to the substrate. Thismay be because diffusivity depends on temperature, and the cooledsubstrate may create a temperature gradient between itself and the COPhead. Using helium as a delivery gas may mitigate the reduction indiffusive organic vapor transport near the substrate. Diffusivity oforganic material in the incoming argon confinement flow 1404 may beabout 25% of the delivery flow. The lower diffusivity of organic vaporin the confinement flow may make it more effective at blocking thespread of organic vapor beyond the confines of the COP head. Becauseconvection predominates over diffusion in the confinement gas, anyorganic material leaving the deposition zone is drawn into the exhaustaperture 702 by the confinement gas flow.

A preferred embodiment of COP may include co-deposition capability. Aco-deposition COP head may contain, or may be in fluid communicationwith, multiple organic vapor sources. Effluent vapors from thesemultiple sources may mix upstream of the delivery channel and depositonto the substrate. The fraction of organic vapor from each source inthe mixture may be determined by a combination of the delivery gas flowrate through each source and the temperature to which each sourcecrucible is heated.

A COP with co-deposition capability may be useful for growing gradedorganic thin films. In a graded film, the concentration of components ina multicomponent film may be graded across the thickness of the film.For example, the concentration of dopant can be varied across the depthof the emissive layer of an OLED to increase efficiency and lifetime(Erickson and Holmes 2014). Conventional deposition techniques maydeposit on the whole substrate at once, so controlling a gradeddeposition may be difficult. Since COP prints a portion of a substrateat a time, it may build a graded layer by evenly printing a desiredregion with a thin film of uniform composition, and may print over thesame region with uniform thin films of monotonically varying compositionuntil a layer with the desired thickness and component grading isdeposited. The sequential films stacked to make the graded layer may bedeposited by changing the process variables of a single COP head witheach pass. Alternately, multiple COP heads, each depositing the samematerial set in different ratios may pass over the substrate in series.

FIG. 15 shows a COP head with multiple sets of delivery and exhaustapertures arranged in a linear array according to an embodiment of thedisclosed subject matter. Sets of delivery and exhaust apertures 1501,as shown singly in FIG. 5, may be arranged on a single COP head 501.These depositor units may be separated along the length of the head byspacers 1502. As shown in FIG. 5 and described above, the COP head 501may be surrounded by a chiller plate 507 and dedicated confinement gassources 506. This configuration may have many potential applications.For example, the widths and positions of spacers may be chosen to avoiddepositing organic thin film on specific areas of a substrate when theCOP head passes over them. This may permit mask-free deposition by COPon substrates with features like encapsulation zones or busline tocathode interconnects. In another application, adjacent depositors mayeach overwrite a given printed zone on multiple passes. If eachdepositor deposits a different material mixture, a graded or multilayerfilm may be produced.

The embodiments of the disclosed subject matter present a confinedorganic printing (COP) source which may deposit material over acontrollable, localized area of a substrate, without the use of masks todefine patterned areas. Deposition uniformity and selectivity may beachieved by control of the environment within a small region of thechamber moving relative to the substrate rather than by creating asevere environment within the entire chamber. The chamber may not becomecontaminated with organic vapor. The chamber may not need to be hotwalled and may contain a variety of additional equipment for additionalprocess steps.

The chamber may not operate at high vacuum (<10⁻⁶ Torr), but at a higherpressure (>10 Torr). This may permit non-vacuum compatible items to beincorporated into process design. Additionally, COP may facilitate thefabrication of devices having a large area and/or graded organic thinfilms.

It is understood that the various embodiments described herein are byway of example only, and are not intended to limit the scope of theinvention. For example, many of the materials and structures describedherein may be substituted with other materials and structures withoutdeviating from the spirit of the invention. The present invention asclaimed may therefore include variations from the particular examplesand preferred embodiments described herein, as will be apparent to oneof skill in the art. It is understood that various theories as to whythe invention works are not intended to be limiting.

1. A system comprising: one or more print heads that eject organic vaporladen gas into a cold-walled chamber and withdraw chamber gas, one ormore distribution nozzles disposed on a chiller plate that surrounds theone or more print heads, wherein the one or more distribution nozzlesoutput confinement gas to isolate the one or more print heads from thechamber ambient, wherein vapor ejected from the one or more print headsis incident on, and condenses onto, a deposition surface within thecold-walled chamber, and wherein the deposition surface moves relativeto the one or more print heads in a direction orthogonal to a platennormal and a linear extent of the manifold, wherein the volumetric flowof gas withdrawn by the one or more print heads from the cold-walledchamber is greater than the volumetric flow of gas injected into thecold-walled chamber by the one or more print heads, wherein the netoutflow of gas from the cold-walled chamber through the one or moreprint heads prevents organic vapor from diffusing beyond the extent ofthe gap between the one or more print heads and a deposition surface,and wherein the one or more print heads are configured so that long axesof delivery and exhaust apertures are perpendicular to a printdirection.
 2. The system of claim 1, wherein the vapor distributionmanifold is formed from perforated sheets of metal.
 3. The system ofclaim 1, wherein the vapor distribution manifold is joined to asurrounding chamber wall via one or more connections, and wherein theconnections are not heated.
 4. The system of claim 1, furthercomprising: a cold-walled process chamber that includes the vapordistribution manifold and an aperture assembly of the one or more printheads that both ejects organic vapor laden inert delivery gas into thecold-walled process chamber and withdraws chamber gas, wherein the vapordistribution manifold ejects vapor that is incident on, and condensesonto, a deposition surface within the cold-walled process chamber, andwherein the deposition surface is configured to move relative to theprint head in a direction orthogonal to the deposition surface normaland a linear extent of the vapor distribution manifold.
 5. (canceled) 6.The system of claim 4, wherein the ejected vapor is incident on, andcondenses onto, the deposition surface within the cold-walled processchamber without a shadow mask.
 7. The system of claim 1, wherein thedeposition surface is a platen.
 8. The system of claim 7, wherein theplaten is configured to hold a substrate.
 9. The system of claim 7,wherein the platen is configured to be cooled by a cooling device. 10.The system of claim 1, further comprising: a deposition aperture todeposit gaseous precursors or substances as deposition materials,wherein the deposition materials are confined to a volume defined by thearea under the deposition apertures by a confining flow and localizedexhaust.
 11. The system of claim 10, wherein a shape of the depositionaperture is amorphous.
 12. The system of claim 10, wherein a shape ofthe deposition aperture matches an unmasked area of a substrate on whichthe deposition materials are deposited.
 13. The system of claim 12,wherein the unmasked area defines an active device.
 14. The system ofclaim 12, wherein the unmasked area has been previously processed. 15.The system of claim 12, wherein a masked area protects the substratefrom the deposition materials.
 16. The system of claim 15, wherein themasked area is removed after the deposition material are deposited,wherein the removal of the masked area is by subsequent processing. 17.A method of fabricating an organic light emitting device (OLED), themethod comprising: depositing a hole transport layer (HTL) with aselective area confined organic printer (COP) in a process chamber thatincludes an organic vapor jet printing (OVJP) print apparatus; anddepositing at least one selected from the group consisting of: at leastone emissive layer with the OVJP print apparatus when the deposition ofthe HTL is completed; and the at least one emissive layer concurrentlywith the HTL, but on top of the HTL layer, wherein the HTL is depositedby COP and the EML is deposited by OVJP.
 18. (canceled)
 19. A method offabricating an organic light emitting device (OLED) using one or moreconfined organic printer (COP) heads, the method comprising: depositingan organic thin film layer with graded doping in a plurality of passesby depositing material of varying composition with each pass, wherein atleast one is selected from the group consisting of: the composition ofthe material deposited by a single COP head of the one or more COP headsvaries with each pass; and a plurality of the COP heads deposit thematerial of different composition on a substrate in series, wherein thematerial composition deposited by each COP head is constant in time. 20.(canceled)
 21. The method of claim 19, further comprising: depositing aplurality of organic layers containing different chemical species withthe plurality of the COP heads.